Fiber-Reinforced EVOH Sheet Orientation for Hydrogen Barrier Strength
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Solution Overview
Problem
Fiber-reinforced plastics (FRPs) with polyamide matrices lack sufficient flexural strength and hydrogen barrier properties, and alternative resin matrices have not been adequately investigated for applications requiring gas barrier properties.
Innovation Solution
A fiber-reinforced ethylene-vinyl alcohol copolymer (EVOH) sheet or tape containing continuous fibers oriented in the machine direction (MD) with a degree of orientation of 2 or less, combined with ethylene unit content of 15-50 mol% and EVOH content of 20-80 mass%, optionally with acid modified polyolefin, to enhance flexural strength and hydrogen barrier properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polyamide is used as the matrix resin for fiber-reinforced plastics, then adhesiveness to carbon fibers and strength are improved, but hydrogen barrier properties become insufficient
Solution Approach 1:
The patent uses a composite material structure combining EVOH resin with continuous fibers (carbon fibers, glass fibers, aramid fibers, etc.) to achieve both mechanical strength and hydrogen barrier properties. The EVOH matrix provides excellent hydrogen barrier properties while the continuous fiber reinforcement provides the necessary mechanical strength, resolving the contradiction between strength and barrier properties.
Solution Approach 2:
The patent specifies precise parameter ranges for the EVOH resin including ethylene unit content (15-50 mol%), degree of polymerization (50-200), and fiber orientation degree (≤2.0) to optimize both strength and hydrogen barrier properties. By controlling these parameters within specific ranges, the material achieves simultaneous improvement in both characteristics.
2Strength
If fibers are highly oriented in the machine direction to improve flexural strength, then flexural strength increases, but hydrogen barrier properties deteriorate
Solution Approach 1:
The patent identifies a critical parameter threshold where the degree of fiber orientation is 2.0 or less. This specific parameter control allows the material to maintain both high flexural strength (through fiber reinforcement) and excellent hydrogen barrier properties (by preventing excessive fiber alignment that would create pathways for hydrogen permeation).
Solution Approach 2:
The patent creates different local structures: the EVOH matrix provides hydrogen barrier properties in the resin phase, while the continuous fibers provide mechanical strength. The controlled low orientation degree ensures that these two functions are distributed appropriately without one compromising the other.
Data Source
Figure 1
AI summary
A fiber-reinforced ethylene-vinyl alcohol copolymer sheet or tape contains an ethylene-vinyl alcohol copolymer (A) and continuous fibers, wherein the continuous fibers are oriented in an MD direction to have a degree of orientation of 2 or less on average obtained by a specific equation. Thus, the fiber-reinforced ethylene-vinyl alcohol copolymer sheet or tape with excellent flexural strength and excellent hydrogen barrier properties is provided.